Backlight modules are important components to LCD (liquid crystal display) panels. Since liquid crystals will not emit light, a backlight module is used to provide sufficient and uniform light to the panel so that images can be displayed normally.
Thereby, backlight modules are important components in determination of the performance of the LCD panels. There are two kinds of the backlight modules being used currently. One has single one light source (currently, the cool cathode fluorescent light is used) which is placed at one lateral side of the modules, and is called as lateral lighting backlight modules. The other has a plurality of light sources which are placed below the panels, and is called as directly lighting backlight devices. In the directly lighting backlight device, most of the cool cathode fluorescent lights have straight lamp tubes.
Referring to FIG. 5, the cool cathode fluorescent lights for the directly lighting backlight devices are illustrated. A plurality of straight lamp tubes are spacedly arranged and are placed below a guide plate. However, the lamp tubes only provide light at two sides, while the other two sides have no light. Thereby, dead portions are generated. As a result a center portion of the liquid crystal panel is lighter, and a periphery portion of the liquid crystal panel is darker. Thereby, the uniformity is not preferred.
Thereby, U shape lamp tubes are developed. With reference to FIG. 6, the U shape lamp tubes are used with straight lamp tubes. A U shape lamp tube is arranged between two straight lamp tubes. The bending portion of the U shape lamp tube provides light to lateral sides. However, there is only one bending portion which provides light to one lateral side. The other lateral side has no light. Thereby, the defect in above prior art can not be resolved completely.
For computer game machines, the above mentioned U shape lamp tubes can not provide sufficient light to players. Moreover, the prior arts still have the following deficiencies.
The time period for arranging the lamp tubes are too long, even U shape lamp tubes are used with the straight lamp tubes, the time required is still long. Thereby, the more the number of backlight modules, the more the number of the connectors for controlling the lamp tubes to light up synchronously and thus the cost is high. Furthermore, the more the number of the lamp tubes, the complication the design of the converter for controlling the voltage and stability of the lamp tubes.